Hi Joseph,
>Hardware platform :
> Dell PowerEdge 2450 bipro PIII/733,
> 2Gb RAM,
> integrated hardware RAID crontroller (PERC3)
> with 2x18Gb disks configured
> in RAID1 (mirroring) mode.
>
>Operating system:
> Linux RedHat 6.2 (kernel 2.2.14 SMP)
>[...]
> I tried to use --safe-mode but I had to turn it off
> after a few minutes, the server was so slow (less than
> 90 queries/s) that it made the webserver frontend almost
> unusable (it needs to do at least 250 to 300 queries/s
> to keep up with web requests).
>[...]
>Does anybody know if one of these operations could help ?
>
>Any other advice ?
>(Remember, this is an heavily loaded webserver, I cannot
>shutdown database service for more than a few minutes)
hmm, this soundy like the problem I *had* in october 2000 with mysql
3.23.26 having a comparable load (100 to 400 q/s) on a server with 8
Pentium-III XEON processors running kernel 2.2.16-2GB-SMP. While using
"mysqladmin status" in a loop for a longer time I found out that mysql
crashed at about 420 processes what caused these damaged tables.
I got a hint about this behavior after searching these lists and
installed a patch for "linuxthreads". After this had to restart the
server once and everything worked fine up to 950 processes. The next
limit was the process-limit (max. 1024 userprocesses) but this can be
raised in the kernel-sources and by setting this value with ulimit
afterwards. You should not forget to set the nr. of file-descriptors
to a much higher value for the running shell you start mysql from,
(eg: echo "8192" > /proc/sys/fs/file-max; echo "24576" >
/proc/sys/fs/inode-max; ulimit -n 8192). After all this done the
server works well with up to 1800 concurrent processes (maybe even
higher, but we had no more load ;-) and 1000 q/s.
Regards und good luck!
Jan Tegtmeier
NetGate Internetservice / Germany
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